Science is a systematic enterprise that builds and organizes knowledge in the form of testableexplanations and predictions about the universe.[1][2]
Chronology of the universe as deduced by the prevailing Big Bang theory, a result from science and obtained knowledge
Science may be as old as the human species,[3] and some of the earliest archeological evidence for scientific reasoning is tens of thousands of years old.[4] The earliest written records in the history of science come from Ancient Egypt and Mesopotamia in around 3000 to 1200 BCE.[5][6] Their contributions to mathematics, astronomy, and medicine entered and shaped Greek natural philosophy of classical antiquity, whereby formal attempts were made to provide explanations of events in the physical world based on natural causes.[5][6] After the fall of the Western Roman Empire, knowledge of Greek conceptions of the world deteriorated in Western Europe during the early centuries (400 to 1000 CE) of the Middle Ages,[7] but was preserved in the Muslim world during the Islamic Golden Age.[8]
The recovery and assimilation of Greek works and Islamic inquiries into Western Europe from the 10th to 13th century revived "natural philosophy",[7][9] which was later transformed by the Scientific Revolution that began in the 16th century[10] as new ideas and discoveries departed from previous Greek conceptions and traditions.[11][12] The scientific method soon played a greater role in knowledge creation and it was not until the 19th century that many of the institutional and professional features of science began to take shape;[13][14] along with the changing of "natural philosophy" to "natural science".[15]
Modern science is typically divided into three major branches:[16] natural sciences (e.g., biology, chemistry, and physics), which study the physical world; the social sciences (e.g., economics, psychology, and sociology), which study individuals and societies;[17][18] and the formal sciences (e.g., logic, mathematics, and theoretical computer science), which study formal systems, governed by axioms and rules.[19][20] There is disagreement whether the formal sciences are science disciplines,[21][22][23] because they do not rely on empirical evidence.[24][22] Applied sciences are disciplines that use scientific knowledge for practical purposes, such as in engineering and medicine.[25][26][27]
New knowledge in science is advanced by research from scientists who are motivated by curiosity about the world and a desire to solve problems.[28][29] Contemporary scientific research is highly collaborative and is usually done by teams in academic and research institutions,[30]government agencies, and companies.[31][32] The practical impact of their work has led to the emergence of science policies that seek to influence the scientific enterprise by prioritizing the ethical and moral development of commercial products, armaments, health care, public infrastructure, and environmental protection.
Etymology
Look up science in Wiktionary, the free dictionary.
The word science has been used in Middle English since the 14th century in the sense of "the state of knowing". The word was borrowed from the Anglo-Norman language as the suffix -cience, which was borrowed from the Latin word scientia, meaning "knowledge, awareness, understanding". It is a noun derivative of the Latin sciens meaning "knowing", and undisputedly derived from the Latin sciō, the present participlescīre, meaning "to know".[33]
There are many hypotheses for science's ultimate word origin. According to Michiel de Vaan, Dutch linguist and Indo-Europeanist, sciō may have its origin in the Proto-Italic language as *skije- or *skijo- meaning "to know", which may originate from Proto-Indo-European language as *skh1-ie, *skh1-io, meaning "to incise". The Lexikon der indogermanischen Verben proposed sciō is a back-formation of nescīre, meaning "to not know, be unfamiliar with", which may derive from Proto-Indo-European *sekH- in Latin secāre, or *skh2-, from *sḱʰeh2(i)- meaning "to cut".[34]
In the past, science was a synonym for "knowledge" or "study", in keeping with its Latin origin. A person who conducted scientific research was called a "natural philosopher" or "man of science".[35]: 3–15 In 1833, William Whewell coined the term scientist and the term first appeared in literature one year later in Mary Somerville's On the Connexion of the Physical Sciences, published in the Quarterly Review.[36]
History
Main article: History of science
Earliest roots
Main article: History of science in early cultures
The Plimpton 322 tablet by the Babylonians records Pythagorean triples, written in about 1800 BCE
Science has no single origin. Rather, scientific methods emerged gradually over the course of thousands of years, taking different forms around the world, and few details are known about the very earliest developments. Some of the earliest evidence for scientific reasoning is tens of thousands of years old,[4] and women likely played a central role in prehistoric science,[37] as did religious rituals.[38] Some Western authors have dismissed these efforts as "protoscientific".[39]
Direct evidence for scientific processes becomes clearer with the advent of writing systems in early civilizations like Ancient Egypt and Mesopotamia.[5] Although the words and concepts of "science" and "nature" were not part of the conceptual landscape at the time, the ancient Egyptians and Mesopotamians made contributions that would later find a place in Greek and medieval science: mathematics, astronomy, and medicine.[40][5] From the 3rd millennium BCE, the ancient Egyptians developed a decimal numbering system,[41] solved practical problems using geometry,[42] and developed a calendar.[43] Their healing therapies involved drug treatments and the supernatural, such as prayers, incantations, and rituals.[5]
The ancient Mesopotamians used knowledge about the properties of various natural chemicals for manufacturing pottery, faience, glass, soap, metals, lime plaster, and waterproofing.[44] They studied animal physiology, anatomy, behavior, and astrology for divinatory purposes.[45] The Mesopotamians had an intense interest in medicine[44] and the earliest medical prescriptions appeared in Sumerian during the Third Dynasty of Ur.[46] They seem to study scientific subjects which have practical or religious applications and have little interest of satisfying curiosity.[44]
Classical antiquity
Main article: History of science in classical antiquity
Plato's Academy mosaic, made between 100 BCE to 79 AD, shows many Greek philosophers and scholars
In classical antiquity, there is no real ancient analog of a modern scientist. Instead, well-educated, usually upper-class, and almost universally male individuals performed various investigations into nature whenever they could afford the time.[47] Before the invention or discovery of the concept of phusis or nature by the pre-Socratic philosophers, the same words tend to be used to describe the natural "way" in which a plant grows,[48] and the "way" in which, for example, one tribe worships a particular god. For this reason, it is claimed that these men were the first philosophers in the strict sense and the first to clearly distinguish "nature" and "convention".[49]: 209
The early Greek philosophers of the Milesian school, which was founded by Thales of Miletus and later continued by his successors Anaximander and Anaximenes, were the first to attempt to explain natural phenomena without relying on the supernatural.[50] The Pythagoreans developed a complex number philosophy[51]: 467–68 and contributed significantly to the development of mathematical science.[51]: 465 The theory of atoms was developed by the Greek philosopher Leucippus and his student Democritus.[52][53] The Greek doctor Hippocrates established the tradition of systematic medical science[54][55] and is known as "The Father of Medicine".[56]
A turning point in the history of early philosophical science was Socrates' example of applying philosophy to the study of human matters, including human nature, the nature of political communities, and human knowledge itself. The Socratic method as documented by Plato's dialogues is a dialectic method of hypothesis elimination: better hypotheses are found by steadily identifying and eliminating those that lead to contradictions. The Socratic method searches for general commonly-held truths that shape beliefs and scrutinizes them for consistency.[57] Socrates criticized the older type of study of physics as too purely speculative and lacking in self-criticism.[58]
Aristotle in the 4th century BCE created a systematic program of teleological philosophy.[59] In the 3rd century BCE, Greek astronomer Aristarchus of Samos was the first to propose a heliocentric model of the universe, with the Sun at the center and all the planets orbiting it.[60] Aristarchus's model was widely rejected because it was believed to violate the laws of physics,[60] while Ptolemy's Almagest, which contains a geocentric description of the Solar System, was accepted through the early Renaissance instead.[61][62] The inventor and mathematician Archimedes of Syracuse made major contributions to the beginnings of calculus.[63]Pliny the Elder was a Roman writer and polymath, who wrote the seminal encyclopedia Natural History.[64][65][66]
Middle Ages
Main article: History of science § Middle Ages
The first page of Vienna Dioscurides depicts a peacock, made in the 6th century
Due to the collapse of the Western Roman Empire, the 5th century saw an intellectual decline in western Europe.[67]: 307, 311, 363, 402 During the period, Latin encyclopedists such as Isidore of Seville preserved the majority of general ancient knowledge.[68] In contrast, because the Byzantine Empire resisted attacks from invaders, they were able to preserve and improve prior learning. John Philoponus, a Byzantine scholar in the 500s, started to question Aristotle's teaching of physics, noting its flaws.[67]: 307, 311, 363, 402 His criticism served as an inspiration to medieval scholars and Galileo Galilei, who ten centuries later extensively cited his works.[67][69]
During late antiquity and the early Middle Ages, natural phenomena were mainly examined via the Aristotelian approach. The approach includes Aristotle's four causes: material, formal, moving, and final cause.[70] Many Greek classical texts were preserved by the Byzantine empire and Arabic translations were done by groups such as the Nestorians and the Monophysites. Under the Caliphate, these Arabic translations were later improved and developed by Arabic scientists.[71] By the 6th and 7th centuries, the neighboring Sassanid Empire established the medical Academy of Gondeshapur, which is considered by Greek, Syriac, and Persian physicians as the most important medical center of the ancient world.[72]
The House of Wisdom was established in Abbasid-era Baghdad, Iraq,[73] where the Islamic study of Aristotelianism flourished[74] until the Mongol invasions in the 13th century. Ibn al-Haytham, better known as Alhazen, began experimenting as a means to gain knowledge[75][76] and disproved Ptolemy's theory of vision[77]: Book I, [6.54]. p. 372 Avicenna's compilation of the Canon of Medicine, a medical encyclopedia, is considered to be one of the most important publications in medicine and used until the 18th century.[78]
By the eleventh century, most of Europe had become Christian,[7] and in 1088, the University of Bologna emerged as the first university in Europe.[79] As such, demand for Latin translation of ancient and scientific texts grew,[7] a major contributor to the Renaissance of the 12th century. Renaissance scholasticism in western Europe flourished, with experiments done by observing, describing, and classifying subjects in nature.[80] In the 13rd century, medical teachers and students at Bologna began opening human bodies, leading to the first anatomy textbook based on human dissection by Mondino de Luzzi.[81]
Renaissance
Main articles: Scientific Revolution and Science in the Renaissance
Drawing of the heliocentric model as proposed by the Copernicus's De revolutionibus orbium coelestium
New developments in optics played a role in the inception of the Renaissance, both by challenging long-held metaphysical ideas on perception, as well as by contributing to the improvement and development of technology such as the camera obscura and the telescope. At the start of the Renaissance, Roger Bacon, Vitello, and John Peckham each built up a scholastic ontology upon a causal chain beginning with sensation, perception, and finally apperception of the individual and universal forms of Aristotle.[77]: Book I A model of vision later known as perspectivism was exploited and studied by the artists of the Renaissance. This theory uses only three of Aristotle's four causes: formal, material, and final.[82]
In the sixteenth century, Nicolaus Copernicus formulated a heliocentric model of the Solar System, stating that the planets revolve around the Sun, instead of the geocentric model where the planets and the Sun revolve around the Earth. This was based on a theorem that the orbital periods of the planets are longer as their orbs are farther from the centre of motion, which he found not to agree with Ptolemy's model.[83]
Johannes Kepler and others challenged the notion that the only function of the eye is perception, and shifted the main focus in optics from the eye to the propagation of light.[82][84] Kepler is best known, however, for improving Copernicus' heliocentric model through the discovery of Kepler's laws of planetary motion. Kepler did not reject Aristotelian metaphysics and described his work as a search for the Harmony of the Spheres.[85] Galileo had made significant contributions to astronomy, physics and engineering. However, he became persecuted after Pope Urban VIII sentenced him for writing about the heliocentric model.[86]
The printing press was widely used to publish scholarly arguments, including some that disagreed widely with contemporary ideas of nature.[87] Francis Bacon and René Descartes published philosophical arguments in favor of a new type of non-Aristotelian science. Bacon emphasized the importance of experiment over contemplation, questioned the Aristotelian concepts of formal and final cause, promoted the idea that science should study the laws of nature and the improvement of all human life.[88] Descartes emphasized individual thought and argued that mathematics rather than geometry should be used to study nature.[89]
Age of Enlightenment
Main article: Science in the Age of Enlightenment
Title page of the 1687 first edition of Philosophiæ Naturalis Principia Mathematica by Issac Newton
At the start of the Age of Enlightenment, Isaac Newton formed the foundation of classical mechanics by his Philosophiæ Naturalis Principia Mathematica, greatly influencing future physicists.[90] Gottfried Wilhelm Leibniz incorporated terms from Aristotelian physics, now used in a new non-teleological way. This implied a shift in the view of objects: objects were now considered as having no innate goals. Leibniz assumed that different types of things all work according to the same general laws of nature, with no special formal or final causes.[91]
During this time, the declared purpose and value of science became producing wealth and inventions that would improve human lives, in the materialistic sense of having more food, clothing, and other things. In Bacon's words, "the real and legitimate goal of sciences is the endowment of human life with new inventions and riches", and he discouraged scientists from pursuing intangible philosophical or spiritual ideas, which he believed contributed little to human happiness beyond "the fume of subtle, sublime or pleasing [speculation]".[92]
Science during the Enlightenment was dominated by scientific societies[93] and academies, which had largely replaced universities as centers of scientific research and development. Societies and academies were the backbones of the maturation of the scientific profession. Another important development was the popularization of science among an increasingly literate population.[94]: 82–83 Enlightenment philosophers chose a short history of scientific predecessors – Galileo, Boyle, and Newton principally – as the guides to every physical and social field of the day.[95]
The 18th century saw significant advancements in the practice of medicine[96] and physics;[97] the development of biological taxonomy by Carl Linnaeus;[98] a new understanding of magnetism and electricity;[99] and the maturation of chemistry as a discipline.[100]: 265 Ideas on human nature, society, and economics evolved during the Enlightenment. Hume and other Scottish Enlightenment thinkers developed A Treatise of Human Nature, which was expressed historically in works by authors including James Burnett, Adam Ferguson, John Millar and William Robertson, all of whom merged a scientific study of how humans behaved in ancient and primitive cultures with a strong awareness of the determining forces of modernity.[101] Modern sociology largely originated from this movement.[102] In 1776, Adam Smith published The Wealth of Nations, which is often considered the first work on modern economics.[103]
19th century
Main article: 19th century in science
The first diagram of an evolutionary tree made by Charles Darwin in 1837
During the nineteenth century, many distinguishing characteristics of contemporary modern science began to take shape. Some of them are: the transformation of the life and physical sciences, frequent use of precision instruments, emergence of terms such as "biologist", "physicist", "scientist", increased professionalization of those studying nature, scientists gained cultural authority over many dimensions of society, industrialization of numerous countries, thriving of popular science writings and emergence of science journals.[104] During the late 19th century, psychology emerged as a separate discipline from philosophy when Wilhelm Wundt founded the first laboratory for psychological research in 1879.[105]
During the mid-19th century, Charles Darwin and Alfred Russel Wallace independently proposed the theory of evolution by natural selection in 1858, which explained how different plants and animals originated and evolved. Their theory was set out in detail in Darwin's book On the Origin of Species, published in 1859.[106] Separately, Gregor Mendel presented his paper, "Experiments on Plant Hybridization" in 1865,[107] which outlined the principles of biological inheritance, serving as the basis for modern genetics.[108]
Early in the 19th century, John Dalton suggested the modern atomic theory, based on Democritus's original idea of indivisible particles called atoms.[109] The laws of conservation of energy, conservation of momentum and conservation of mass suggested a highly stable universe where there could be little loss of resources. However, with the advent of the steam engine and the industrial revolution there was an increased understanding that not all forms of energy have the same energy qualities, the ease of conversion to useful work or to another form of energy.[110] This realization led to the development of the laws of thermodynamics, in which the free energy of the universe is seen as constantly declining: the entropy of a closed universe increases over time.[a]
The electromagnetic theory was established in the 19th century by the works of Hans Christian Ørsted, André-Marie Ampère, Michael Faraday, James Clerk Maxwell, Oliver Heaviside, and Heinrich Hertz. The new theory raised questions that could not easily be answered using Newton's framework. The discovery of X-rays inspired the discovery of radioactivity by Henri Becquerel and Marie Curie in 1896,[113] Marie Curie then became the first person to win two Nobel prizes.[114] In the next year came the discovery of the first subatomic particle, the electron.[115]
20th century
Main article: 20th century in science
First global view of the ozone hole in 1983, using a space telescope
In the first half of the century, the development of antibiotics and artificial fertilizers improved human living standards globally.[116][117] Harmful environmental issues such as ozone depletion, ocean acidification, eutrophication and climate change came to the public's attention and caused the onset of environmental studies.[118]
During this period, scientific experimentation became increasingly larger in scale and funding.[119] The extensive technological innovation stimulated by World War I, World War II, and the Cold War led to competitions between global powers, such as the Space Race[120]: 3–5 and nuclear arms race.[121] Substantial international collaborations were also made, despite armed conflicts.[122]
In the late 20th century, active recruitment of women and elimination of sex discrimination greatly increased the number of women scientists, but large gender disparities remained in some fields.[123] The discovery of the cosmic microwave background in 1964[124] led to a rejection of the steady-state model of the universe in favor of the Big Bang theory of Georges Lemaître.[125]
The century saw fundamental changes within science disciplines. Evolution became a unified theory in the early 20th-century when the modern synthesis reconciled Darwinian evolution with classical genetics.[126] Albert Einstein's theory of relativity and the development of quantum mechanics complement classical mechanics to describe physics in extreme length, time and gravity.[127][128] Widespread use of integrated circuits in the last quarter of the 20th century combined with communications satellites led to a revolution in information technology and the rise of the global internet and mobile computing, including smartphones. The need for mass systematization of long, intertwined causal chains and large amounts of data led to the rise of the fields of systems theory and computer-assisted scientific modeling.[129]
21st century
Main article: 21st century § Science and technology
Radio light image of M87* black hole, made by the earth-spanning Event Horizon Telescope array in 2019
The Human Genome Project was completed in 2003 by identifying and mapping all of the genes of the human genome.[130] The first induced pluripotent human stem cells were made in 2006, allowing adult cells to be transformed into stem cells and turn to any cell type found in the body.[131] With the affirmation of the Higgs boson discovery in 2013, the last particle predicted by the Standard Model of particle physics was found.[132] In 2015, gravitational waves, predicted by general relativity a century before, were first observed.[133][134] In 2019, the international collaboration Event Horizon Telescope presented the first direct image of a black hole's accretion disk.[135]
Branches
Modern science is commonly divided into three major branches: natural science, social science, and formal science.[16] Each of these branches comprises various specialized yet overlapping scientific disciplines that often possess their own nomenclature and expertise.[136] Both natural and social sciences are empirical sciences,[137] as their knowledge is based on empirical observations and is capable of being tested for its validity by other researchers working under the same conditions.[138]
Natural science
Natural science is the study of the physical world. It can be divided into two main branches: life science and physical science. These two branches may be further divided into more specialized disciplines. For example, physical science can be subdivided into physics, chemistry, astronomy, and earth science. Modern natural science is the successor to the natural philosophy that began in Ancient Greece. Galileo, Descartes, Bacon, and Newton debated the benefits of using approaches which were more mathematical and more experimental in a methodical way. Still, philosophical perspectives, conjectures, and